S4C is a Welsh language free-to-air public broadcast television channel. Launched on 1 November 1982, it was the first television channel to be aimed specifically at a Welsh-speaking audience. S4C's headquarters are based in Carmarthen, at the University of Wales Trinity Saint David's creative and digital centre, Yr Egin. It also has regional offices in Caernarfon and Cardiff. As of 2024, S4C had an average of 118 employees. S4C is the fourth-oldest terrestrial television channel in Wales after BBC One, ITV and BBC Two.

Welsh is a Celtic language of the Brittonic subgroup that is native to the Welsh people. Welsh is spoken natively in Wales, by some in England, and in Y Wladfa.